Plugin Variables are not Resolved

Again, check your article in HTML mode. Here's another example from a support case. In wysiwyg mode, the plugin call looked like this:

{plotalot id="23" P1="_product" }

But in html mode it looked like this:

{plotalot id="23" P1="_product</span><span style="font-size: 12.16px;">" }

So Plotalot was looking for a variable named "product</span><span style=".